This is an allusion to the solemn ceremony used by several ancient nations, when they entered into a covenant with each other. The victims, slain as a sacrifice on this occasion, were divided, and and parts laid asunder: the contracting parties then passed between them, imprecating, as a curse on those who violated the sacred compact, that they might in like manner be cut asunder

( Genesis 15:10 .) St. Cyril, in his work against Julian, shows that passing between the divided parts of a victim was used also among the Chaldeans and other people.